Associations and prognostic implications of myocardial tissue injury stages in ST-elevation myocardial infarction using the Canadian Cardiovascular Society classification

Myocardial infarction (MI) involves progressive tissue damage beyond necrosis. The recently proposed Canadian Cardiovascular Society (CCS) classification defines this damage in four stages, potentially optimizing personalized risk stratification and advancing research on cardioprotective treatments. The baseline associations and prognostic implications of this classification remain to be explored.

To compare clinical characteristics across CCS stages and to validate their prognostic implications in patients with ST-elevation myocardial infarction (STEMI) treated by percutaneous coronary intervention (PCI).

We analysed 1,109 STEMI patients included in three prospective studies. Cardiac magnetic resonance (CMR) imaging was performed 3 (interquartile range 2-5) days after MI and patients were classified as follows: stage 1 (aborted MI), stage 2 (MI with necrosis and absence of microvascular injury), stage 3 (MI with necrosis and microvascular obstruction) and stage 4 (MI with necrosis and intramyocardial haemorrhage). This analysis revealed distinct patterns of clinical presentation, biomarker profiles and cardiac function at different CCS stages. There were differences in adverse clinical event rates and mortality between CCS stages (major adverse cardiovascular event [MACE]: 0.7%, 3.4%, 3.1%, 15.7%, p<0.001 and mortality: 0.7%, 1.7%, 0.9%, 6.3%, p<0.001). The CCS stage had a moderate to good predictive value for MACE and mortality (AUC 0.74 [95% CI: 0.68-0.80], p<0.001 and AUC 0.71 [95% CI: 0.61-0.80], p<0.001) at 12 months, respectively.

This study describes clinical characteristics across CCS stages and provides insights into the prognostic implications of the different stages of tissue injury severity in a large cohort of STEMI patients reperfused by PCI. These data should inform the use of CCS stages in future trial designs.